Fluid pump or compressor



May 27, 1930 I w. H. CARRIER A 1,760,475*` FLUID PUMP 0R COMPRESSOR [9096 wl; ,wawwk 107 y ATTORNEYS May 27, 19'30- w, H. CARRIER 1,760,475

FLUID lFUND? OR COMPRETSSOR I Filed Oct. l, 1924 3 Sheets-Sheet 2 W. H. CARRIER FLUID PUMP 0R COMPRESSOR May 27, 1930.

3 Sheets---Shezei'l 5 Filed ont. 1', 1924 .Patented May 27, `19.3.0

' UNITED s'ra'rlzsy PATENT oFF-Ica.

WILLIS Hf CARRIER, 0F ESSEX FELLS, JERSEY, ASSIGNOR TO CARRIER ENGL NEERING CORPORATION, OF NEWARK, NEW ERSEY f FLUID PUMP pa coMPnEssoii.

.Application med ootober 1,

The invention relates to hydraulic gas or vapor umps or compressors, and more particularay to multi-stage centrifugal gas or vapor pumpssin which a. moving liquid body is used as the active pumping medium.

` In the evacpation `or compression of gas or vapor, it has been impracticable with designs heretoforev roposed, lto produce a multistage centri ugal pump using a liquid as the j actlv/e pumping medium, as the liquid could not be held in the second stage, andthepump would therefore be useless. `It has also been impossible to` .produce a`single stage pump of this type constructed as heretoforeprposed, which would produce a high vacuum, have a high efficiency when pumping gas or vapor under pressure, which wouldbe easy to assemble and 'in-which the clearances between the impller and stator could be adjusted closely enough to prevent leakage. Ithas been the practice tol introducev the liquid pumping medium into theA suction .pipe with a result that theports Iin the pump wereV blocked with liquid, thusreducing the etli- .cienc-y. In refrigeration apparatus using a Vchemical lsuchl as dichloroethylene, carbon tetrachloride, etc, as the refrigerating me` dium, it becomes necessary to evacuate leakage air from the condenser during thefopera-i i Ation ofthe syste and the device to be described is especia y adaptedto evacuate this air with a minimum of loss of the refrigeratingjnedium. Y

Jficient method'srf, and apparatus for, separating, scrubbing or purifying gases or mixtures of gases have not heretofore been produced.A Also no effective method has heretofore been-devised of cooling the gases passing through the pump, with the result that a large volume ofl gas or vapor was ,handled at a higher temperature with a corresponding loss in efficiency.V i l An object of the invention, therefore, is to produce a practical and eflicient multi-stage centrifugal pump for gases or vapors'` in l which a liquidis used as an active, pumping medium. ,j

Othfe'r objects. of theinv/Iit-ion are to pro vide a pump ofthe class described which will 5' produce ahighvacuum or will pump `gases or l;

gases or vapors passing through the pump so improve pumping devices and gas treating -pump embodying my invention.

1924. Serial No. 741,082.

vapors under pressure witha high efficiency.; also to provide a pump of the class described which will be easy to assemble and 'disassemble and which will provide means for adjusting the clearance between the impeller and stator to take up for wear; also to introduce the liquid pumping. medium directly intothe impeller without blockin up the gas or vapor port and reducing the e ciency of thepump; lalso to produce a pump which will evacuate the non-condensible gases from the condenser of a refrigeration apparatus with a minimum loss of t e refrigeratingchemical; also to provide an effective meansy for cooling tha.

as to increase the efficiency; also to provide a metliodof separating, scrubbing or purifying gases or mixtures of gases er vapors which will bev highly'V effective; and also toV 0 methods in other respects, as hereinafter specified and` set forth in the claims. In the accompanying drawings Fig. 1 is4 a sideI elevation of a centrifugal f l Fig.. 2 is a central longitudinal sectional y view through the'pump on line 2 2, Fig. 1..y

' Fig. 3 is a central longitudinal sectional view through the pump taken at right angles to the section shown in Fig. 2. 'I

Fig. 4 is a` transverse sectional view through the pump on line 4 4, Fig. 3.

Fig. is atransverse sectional view through .the pump on line 5 5, Fig. 3.

Fig. 6 is a fragmentary sectional view takenon-line 6 6, Fig. 3. Fig.7 is` attransversemsectionalview the pump on line 7 7, Fig. 3. i

F ig. 8 is a sectional view through the pump Online 8 8, Fig. 3. f 9G Fig. 9 is a fragmentary sectional viewl on line 9 9,6. a

I n the pre erred embodiment of the invention, the pump comprises, :briefly stated, a spindle rotatably mounted in a stator casing and carrying rotary impellers. The spindle is preferably but not necessarily positioned through -fwith its axis vertical and is connected to the' shaft of a driving motor by any\ suitable f means. Twoorfmore impellerl wheels are se- 1.00

cured to the spindle, the'wheels being eccentrically arranged within circular impeller chambers in the stator;i their eccentricity `be` ing oppositely dispose to balance the lateral pressures on the impellers. The pumping liquid is caused to iiow througli' the stator and through the impellers in succession so that the gas or vapor is drawn into one impeller,-

compressed by the liquid and delivered to the next impeller'wherelt is further compressed b the liquid and'discharged from the stator. rIhe impellers are provided with suitable adjusting means so that their axial position on the spindle may be varied to maintain the clearance between the' 'stator and impellers as small as possible thus prevent leakage of gas. -The pump shown is also provided with an intercooler through which the gas or vapor 'and liquid passes from one impeller to the .next for cooling and condensing the gas or va r. l

Re erring to the accompanying drawings, 10 indicates a'motor having a base 1 1 and a preferabl vertical shaft 12. The. shaft 12 1s secure concentrically to the upper or outer lend of a spindle 13 by any suitable means, such as a laterally ext-ending pin 14 said spindle being bored out at its upper end to receive said shaft 12. A The pump is conveniently provided with two stages, although more stages may be used, and the moving parts of the first stage consist of an imlpeller 15 having an upwardly extending concentric sleeve lfslidably fitted to the upper end of thespindle 13. The impeller 15 has a hub 17 from whih extend radial blades 18 s of .rotation of the impeller.

having a curvature forwardl in the direction he sleeve lhas a reduced annular sectionA 19 which isrotatably mounted in the adjacent end or top 2O of the pump. The axial position of the im ller 15 on the spindle 13 1s adjustedeby suitable means which are preferably constructed as follows. The upper end of said sleeve is threaded to receive an adjustin nut 21 and a locking nut 22. The upper en of the spinldle 13 has an annular' section 23 of smaller diameter which is threaded to receive a locking nut 24, the nut 21 being positioned between-the nuts-22 and 24. A shoulder 25 is formed on the'spindle 13 `at the bottom 'of the reduced portion 23, and an inwardly extending annular fiangev 26 on the nut 21, seats against said shoulder, -being held, there:

. against by locking nu 24.

The upper ed es of the blades 18 are adapt ed to -be set wit as little clearance a'svpbssible between them and the inner surface 27 of the pump top 4so as to prevent gas leakage from the impeller. A In orderto adjust this clearance in assembly or when it becomes too j great because of lwear, the sleeve 16 is moved relatively to the s indle 13'by means of the nut 21. The impe ler is causedto turn with the shaft, preferably by an internal slot 28 eries ofthe nuts 21 and 24,. adapted to re- 7o ceive spanner wrenches, may be employed forl rotating said nuts and causing the slight movement of the sleeve 16 relative to the spin .dle 13 necessary for properly adjustin clearance between the upper ed" es of the blades 18 and the surface 27. As t e pump is preferably, but not necessarily, designed to' be immersed in a liquid, it is desirable to covthe er the rotating nuts 21, 22 and 24 with an annular guard 31. This liquid fromwhirling an and the liquid thus provides a liquid seal around the nuts and prevents leakage of air into the pump. The guard 31 shown is constructed in two halves provided with perforated ears 32 through which bolts 33 pass to connect the halves together. An annular flange 35 is formed on thejupper end of the guard 31, saidflange being adapted to be bolted to the lower face of the motor base 11 orv other fixed support. The guard^31 is also providedwith internal annular flanges 36 and 37 respectively rotatably fitting the nut 24 and the sleeve 16 below the nuts. l

The pum top 20 is hollow, having an annularspace etween itslupper and lower walls divided by a radial wall 40into a suction chamber 42 and a discharge chamber 43. The chamber 42 is suitably connected 'to a suction pipe 45, and the chamber 43 is suitably connected to a discharge pi e 47. An arcuateport 48 is formed in the ower wall of the (guard prevents the chamber 42 adjacent the inner wall of thev chamber, said port being comparatively narrow adjacent the suction pipe'45, but increasing in width vin the directlonof rotation in the impeller 15 to which it is designed to de liver gas or vapor from 4the suction 'ipe 45. The pump top 20/is also provided wit a hole 49, preferably in a tapped lug 50, adapted to'freceive a liquid pipe 51 .leading from any source of liquid, such -as a pressure tank or centrifugal pump, not shown, if the pump is operated above atmospheric pressure. If the pump is used for maintaining la vacuum, the pipe 51 may be short-or entlrelyomitted so that the refrigeratin liquid in which the pump'is immersed is awn -into the impeller as the pumping medium.

A hole 52 extends obliquely from the hole 49 so as to deliver the liquld entering the hole forming a vortex,

lo charge pipe 57 which are adapted to be secured tothe lower surface of the motor base 11 b means of bolts 58. The lower wall of the. discharge chamber 43 is provided near ythe inner wall of the chamber with an arcuate port 59 which diminishes in width in the direction of rotation of the impeller 15 and is adapted to permit the flow of-liquid,vapor and gas from,

the impeller 175 intoy the chamber 43 and dis- The pump body 56 has an annular chambe V60 in its upper side, eccentric to the impeller,

. which is considerably larger in diameter than 'a comparatively large clearance exists between said impeller blades 18 and wall 61 at a position diametrically opposite. Thus, when the impeller 15i-s rotated at a high speed and a. liquidl enters the impeller chamber through the port 48, the liquid is caused to rotateby theimpeller blades and is thrown outwardly against vthe wall 61 so as to form an arcuate space between the hub 17 and the surface of the liquid. Thus vapor or gas is drawn into the impeller chamberthrough' the port lLS-between the surface ofthe liquid and the hub 17, andas the liquid a ain ap roaches the hub adjacent the port 59, ue to t e' eccen-A tricity ofthe chamber, the gas and some of Lthe liquid is forced out ofthe latter port and out through thedisclarge pipe 47. A shroud 62 is v`impe er 15 integral with the blades 18 so as to: strengthen the same and prevent any gas .leakage fromfth'e im eller blade as the 1mpeller rotates. The oor 63 .of the recessv() has 'a counterbore 64 substantially the same depth and diameter as the shroud 62, in'which -sald shroud rotates freely. i f

`The discharge pipe 47 is connectedA to an intercooler 65,v referably, but not necessarily in the formo a coil, and saidjintercoolerl leads into the second stagesuction pipe 66 which is connected in any suitable way with the second stage; suction chamber 7 O in the pump body 56. The pump and intercooler are preferably submerged .in ya coolingliquid or refrigerating medium contained in a tank 68 having a' cover 68", and the motor base 11 is. arranged soas to'close an opening 69 in said cover through which the pump can'be inserted into and removed from the tank 68. Thus, the gas orvapor which has been coini' pressed and heated, due tothe increase 1n` pressure inthe first stage'of the pm passes through the intercooler which. 1s -su merged inthe cooling 'liqui'd,`said gas being mixedA with the cold'liquid pum -in' mediumr'om` v the I ir'st stage, softhat it `1 sje cientl 'co'oled "-"aridfreduccdtoL a smaller.' volume.: he1cool ing is accomplished externally and mdlrectly Breferably formed on the bottom of the `by the cooling liquid in the tank and the gas is cooled directly by the coolli' uid pumping medium which flows through t e intercooler 65 in contact with the gas so that a very ellicientl cooling is' accomplished. 'When Vthev pump is used for the evacuation*l of air or other non-condensible gases 'from'the con-l denser of a refrigerati'on'system4 in which a. volatile refrigerant such as dichloroethylene, carbon tetrachloride, etc. isemployed, it is very convenient to pass some o the refrigerating liquid through the pump as the pumping medium. In this case the liquid refrigv erant is sup-plied to the tank 68 and is utilized j as pumping medium, and aids in cooling and condensing out any of the volatile chemicals contained in thegases as the pumping liquid aoy passes through the first stage, intercooler and second stage, sothat the loss of the refrigerl ant is reducedto a minimum.

v The pump body 56 is hollow and divided by a bottom 71 anda partition 73 into thev suction chamber70, and discharge chamber 72. An "arcuate, tapering suction port.7 5 is formed in the bottom 71 of the body, increasing in width in -the direction 'of rotation of the second stage impeller 7 6.' The impeller 76 has a hub 77 fittedto thefspindle 13 and radially disposed blades 78l are formed on lsaid hub, said blades curving forwardly in the direction of rotation of said impeller 76. An upper shroud 79 and\lower shroud 80 are vprefere-bl formed on th impeller 76 integral with the lades 78, servi g to-strengthen`the blades and prevent the akage of gas from theimpeller. A port 81 is formed in the shroud 79'between each pair 'of blades 78 adjacent the hub 77, said ports 81 registering lvvith the suction port 75 andfa discharge ort 82 inthe bottom71 of the chamber 72. e Sport 82 is arcuate in form and also ta' ers iny the direction of rotationof the impe 1er 72. A counter-bore 83 is formed in the lower surface of the bottom 71, in which the shroud 7 9 is rotatably fitted'with'a` very small clearance` therebetween so as to prevent the leakage of gas from the impeller 76. Y

' As shown, the'bottom 71 of the ump body 56 is formed with avilange 84 (see, igs. 7 and 8), and is secured by bolts 85 to an annular flange 86 `formed on a pump bottom 87 A plurality of lugs 88 is also formed on theso` as toproperly position the pump bottom 87 relatively to the ump body 56 when-as-A sembling. An annu ar eccentric recess 9() i'sv formed in the top of the;

tum-i said recess being considera ly rger' in di ametcr than the impeller, 76 and havin j its ,bottom 87, f

center at' a distance from the'center o the spindle'. 13. s .The 'internal annular' .walll 91 of: the-recess is thus, spaced with a lvery small clearance at one position of the impelleriao 76 and with a much larger clearance at a position diametricallv opposite to the eccentric s ace 61 of the rst stage, so as to balance t 'e' pressure of the pumping liquid inthe two stages. The li uid pumping medium drawn into the impeller 76 through the port 75, follows the Wall 91 as the impeller 76 rotates at a high speed, so that a space for the gas is left between the hub 77 and the surface of the liquid. The gas therefore enters this space in the impeller 76 through the port 75, and as the liquid pumping medium 1s again forced toward the yhub 77 adjacent the port 82, the gas and some of. the liquid pumping medium is forced out of theimpeller through said port 82 into discharge chamber 72 and out of a discharge pipe 92 secured by any suitable means to said dischar e chamber 72. The pipe 92" leads up- 'as bottom 107 is for'med'on the pump bottom.

and. surrounds the adjusting *nuts and war ly through the motor base 11 to any suit- `able trap or separating device, not shown, which separates the liquid pumping medium from the gas and returns the former 'to thel refrigeratlon system, discharging the gas into the atmos here.. The suction line 45 also leads up t rough the motor base 11 so that the motor and pump may be leasily removed as a unit from thetank cover 68 for inspection v or repairs.

The shroud 80 of the impeller7 6 is rotatably received in a counter-bore 94 in the floor 95 of the recess 90, said counter-bore.

having substantially'the same depth and diameter as the shroud 80. `In order to accurately adjust the clearance between the shroud 79 and the counter-bore 83 to take .up for W\car,qetc., the impeller hub 77 has a downwardly extending sleeve 9 6 -fitted around thespindle 13, vand `said sleevey is threaded to receive an adjusting nut 97 and a lock nut 98 similar to those` in the first stage.l The spindle has a threaded lower end 99 of reduceddiameter forming a'shoulder 100. fAn inwardly extending annular flange 101 on the -nut' 97 is adapted to be forced against the'shoulder 100 by a locking nut 102 va set screw 104 is shown screwed to thevsleeve l96, the inner end of. said screw being re-` ceived by a slot 105 in the spindle 13,l this arrangement also permitting axial movement of the sleeve 96 'relatively to the spindle 13 when the nuts 97, 98 and 102 are adjusted.

A cylindrical casing 106 having ajclosed v lo`wer',ei1d.of the spindle` so as to make a gas tight casing forthe pump. The'vpumptop, bodyvv and bottom are *consecutivelyv secured one tothe Iother so as to ermit easy assem-v bly and the threesections orm a stator which is attached to kthe motor to form a convenientseparating, scrubbing or purifying gases or vapors. Thus a liquid pumping medium may be selected to remove a gas, liquid or vapor from other gases by dissolving out or chemically combining with ingredients of the gas. The gas or vapor remaining is compressed by the pump while the purification or scrubbing action takes place. The gas or vapor is thoroughly mixed with the pumping liquid by the impeller blades it passes through the intake ports of the first and second stage so that the purifying and scrubbing action is thorough.

In the operation, the gas or vapor to be compressed is drawn into the suction chamber 42 of the pump through suction pipe 45 and is then drawn into the impeller 15y through port 48. The liquid pumping medium is introduced into the impeller 15 through hole 52 and through the narrow end of the suction port 48. The liquid follows the eccentric outer wall 61 of the recess' 60 forming a space for the vapors between the surface of said liquid and the hub 17 of the im peller 15. As the impeller 15 continues to rotate, the gas and some of the liquid pump ing medium are forced out of the discharge port 59 as the surface of the liquid again lof the impeller 76 then forces the liquid back ,in contact with the hub .77 so that the gas and some of the liquid pump mediumA flows out of the port 82 into discharge'chamber 72 and out through discharge pipe 92.

'In order to adjust'the clearance between 4the upper'surface of the impeller blades 18 and the lower surfa`ce 27 of the pump top 20, the adjusting nut-.'21 is rotated slightly after loosening the lock nutsl 22 and 24. Then they 'locknuts' 22 and 24 are again tightened, the,

annular fiange26 onthe nut 21 contacts with lthe shoulder. 25 on thespindle 13 so as to properly adjust. said clearance, while the lock nutl 224 prevents any further rotation of the nut21.' Y

The connection described for causing the Aapproachesthe hub 17. When passing out of impeller 76 to rotate -with the spindle 13 also permits ya slight axial omovement therebetween. In order toadjust the clearance betweenthe impeller 76 and the counter-bore 83, the lock nuts 98 and 102 are loosened. The adjusting v nu'ta97 can then be turned slightlyvto adjust said clearance and then the lock nutsi93' and 102 are again tightened toV Having thus described my invention.l

claim as new and desire to secure-by Letters Patent: n y i 1. In a centrifugal pump in which -.a liquid acts as a pumping medium for a gas,'a plurality of rotary impellers arranged in axial alinement and connected to rotate toy gether,"each adapted to cause the rotation,of

the pumping liquid, means for causing the pumping liquid to pass fro one to another of said impellers and be a ted upon by said im ellers in succession .so as to cause ya gas to' e receivedat a low pressure by one irnpeller and delivered at a higher pressure by another impeller, and means for adjusting the lleaka e 3. in vacts as a pumping medium for agas, a pluaxial position of an impellerfto regulate the clearance between. the impeller and Ian .op-- posed part of the pump.

2. In a centrifugal pump in whicha liquid t acts as a'pumping medium for a gas, a'pluralityl ofrotary impellers arranged in axial alinement andconnected to rotate together, eachadapted to cause the rotation of the pumping liquid, means forcausing the pumping liquid to pass from 'one to another of said impellers and be acted upon by saidnimpellers in successiony so as to cause a gasto be received at a low pressure by one impeller and delivered ata higher pressure by another impeller, and means yfor independently adjustingV thev position of said impellers so that the clearance between' the saine and opposing parts of the pump. is regulated to prevent of gas from the impellers.

a centrifugal pump in which a liquidrality of rotary impellers secured to a driven 1 A shaft, each adaptedl to causelthe rotation of the pumping liquid, means `for causing the pumping liquid to pass successively through said impellers so'as to cause a gas to' be receivcd at low 'pressure by one impeller and be delivered at a higher pressure by another impeller, and means for adjusting the axial r position of an impeller relative to said .shaft acts as a pumping me to regulate the clearance between the im- Lpeller and an opposed part of the pump 4. In a centrifugal (pump in which a iquid ium far a gas, a stator,

a driven rotary shaft, an impeller secured to said'shaft inside said stator adapted to cause thev rotationof the pumpin liquid, means for passing the pumping liquzi through said impeller so asyto cause a gas at a low pressure to bereceived by the im eller and discharged from the stator. atpa.,A igli'er pressurefand 'means for adjustingthc position' ofsaid im-A ance therebetween is regulated to prevent leakage of gas from the impeller.

5; In a centrifugal ump in which a liquid acts as apumping me ium for a gas, a stator, a driven rotary shaft, a pluralityof impellers vent leakage ofgas from the impellers.

v 6. In a vacuum gas pump having a gas iii-l l letand a gas outlet, a plurality o-driven impellers, means for successively passing a other of said impellers so that the gas is re- -ceived at a low pressure by one impeller and peller relative to said stator so that the clearfsecured tosaid shaftdnside said stator, each adapted to cause the rotation of the pumping liquid, 'means for successively passing theA `pumping liquid and the gas from oneto andelivered .by another'impeller at a higher t pressure, and means yfor cooling the gas and liquid as they pass from one impeller to another impeller. 1

7. In a vacuum .gas pumphaving a gasinlet and a gas outlet, a plurality of driven 1mpellers, means for successively passing a cold -pumping liquid from' one to another of said impellers so that the gas is received' at a'low pressure by one impellerand delivered by another impeller at aV higher pressure, and an intercooler between two 'of said impellers adapted to conduct the gas andcold liquid therebetween and cool the gas and liquid.

8. In a vacuum gas pump havin a gas y inlet and a gas outlet, a plurality o driven impellers, means for 'successively passing a cold pumping liquidfroin one to another `of said impellers so that a gas is received at a lowqpressure by one impeller and delivered by anothergimpeller at a higher'pressure, an intercooler arranged to conduct the gas and liquid from one impeller to another impeller and cool themduring transfer, and means for cooling the intercooler externally so as to aid in cooling the gas and liquid.

9. :In a pumping device in whlch a liquid acts as .a pumping medium for a gas,

av lurality of rotary impellersv` each adapted) to cause the-rotation of the pumping liquid, means for causing the pumping liquid to Vass successively from one to another of said impellers and be acted upon by-said impellers in succession so as to cause a gas to-be eol received at low pressure by one impeller and be delivered at ahigher'pressure by another impellensaid pumping device having separate inlet ports for. pumping medium.

10. In acentrifu al a stator enclosing said impellers, Aa port in thedgas and .for the? Pump-a y.driven shaft, f 9! plurality 0f impe 1ers secured to' said shaft,

said stator adjacent one 'of said impellers, separate' means for the admission of a pumping.. liquid to said impeller so as to draw a gas at low pressure through said port to said impeller, said impeller beingl adapted to increase the ressure of and. deliver said gas to another impeller, and means for conducting said gas from the second impeller and sald stator r` at a still higher pressure.

11. In a centrifugal pump, a stator, a plurality of rotary impellers arranged in said stator to provide an eccentric space between the stator and each impeller, said spaces for two impellers being oppositely and diametrically disposed to each other, and means for passing a pumping liquid through said stator spaces from one to another of said impellers so that said liquid accomplishes a pumping action on passing'therethrough thus causing a gas at low pressure to be received by one impeller `and delivered by another impeller at a higher pressure.

l2. In a centrifugal pump, a fixed support, a plurality o fstator sections adapted to be successively secured to said fixed support, a driven `VShaftrotatably mounted in said stator sections, a plurality of impellers se- Icured to said shaft in said stator sections, and means for passing a pumping liquid ythrough said stator sections from one to another of said impellers so that a gas at low pressure lis received by one impeller and delivered from another impeller at a higher pressure. j

13. In a centrifugal pump, and in combination, a container kfor a li uid, a stator submerged inthe liquid in t e container, gas inletand discharge connections, a plurahty of rotary impellers arranged in said stator, and means for passing said liquid as a pumping medium through said stator from one to another of said impellers so that a gas at low pressure .is received by-one impeller and delivered from another impeller at a higher pressure.

14. In a centrifu al pump, a stator, a driven shaft rotatablj7 mounted in said stator, a 'plurality of impellers concentrically arranged on said shaft, adjusting nuts associated with said impellers and said shaft and adapted to adjust the position ofsaid impellers axially of said shaft to regulate the distance between said impellers and-'said stator, and means for passing a liquid pumping medium through said stator and impellers so that a gas at low pressure is received by one impeller and delivered from another impeller at a higher ressure.

15.In apumping evice, a pump top, a pump bottom, a pump body secured between said pump top and bottom so as to form a sectional stator, a shaft rotatably mounted in said stator, a low pressure and ahigh vpressure impeller secured to said shaft in said stator, means for causing a pumping liqsaid gas at a higher uid'to be acted upon b said im ellers in succession, and means or intro ucing a l'ow pressure gas to'be compressed into the stator and low pressure impeller and delivering pressure from the second impeller and stator.

16. In a pumping device, a pump top, a pump bottom, a pump body secured between said pump top and bottom so as to form a sectional stator, a shaft rotatablymounted in said stator, a low pressure/and a high pressure impeller secured to said shaft in said stator, means for causing a pumping liquid to be acted upon by said impellers in. succession, means for introducing a low pressure gas to be compressed into-the stator and lowT pressure impeller and delivering said gas at a higher pressure from the second imeller and stator, and means forindependenty adjusting the position of the impellers relative to said stator. f

17. In a vacuum pumping device, a pump top, a pump bottom,' a pump body secured between said pump 'top and bottom so as to form a sectional stator, -a shaft rotatably mounted in said stator, a low pressure and a high pressure impeller secured to said shaft in said stator, means for causing a pumping liquid to be acted upon by said impellers in succession, means for introducing a low pressure gas to be compressed into the stator and v low pressure impeller and cooling the gas as said gas passes from the low pressure to the high pressure impeller.

18. 'In a vacuum pump for gasesutilizing the liquid of the gas as the pumping medium, a plurality of rotary impellers each causing a rotation of the pumping liquid, ymeans for conducting the pumping liquid-(from one impeller to another in succession, means for admitting the gas to the inlet of a low stage impeller and removing it from the outlet of a higher stage impeller, whereby said liquid and gas will' pass together through and between said impellers, and means forf cooling said liquid and gas While passing between said impellers.

19. yIn a vacuum pump for gases utilizing a Working liquid as the umplng medium, a plurality of rotary impe ers, each causing -a rotation of the pumping li uid, a gas inlet l leading to and an outlet lea ing from each impeller, a connection from the outlet ofy one a working liquid as the pumping medium, a

plurality of rotary impellers, Aeach causing a rotation of the pumping liquid, a gas inlet leading to and an outlet leading from each "uid being impeller, a separate liquid inlet leading to one impeller at a point adjacent the gas inlet, a connection from the outlet of4 said one impeller to the inlet of another to cause the gas and some of the pumping liquid to pass in succession through said impellers, and means for cooling said connection whereby the gas and liquidvwill be handled in a cold condition in both impellers.

21. The process of creating a vacuum for a vapor with a rotating body of the liquid of the vapor as the Working fluid, which comprises pumping and compressing the vapor through a plurality of stages with the liquid. of the vapor as the pumping liquid, and cooling the vapor andv liquid between stages to avoid the breaking of the vacuum by a high vapor pressure of the pumping liquid.

22. The process of pumping a gas to create a vacuum which comprises compressing and transferring said gas with a rotating body of the liquid of said gas as the pumping medium, through. a plurality of stages, and

`cooling the gas between stages of compression to decrease its volume to provide a low vapor pressure of the pumping liquid, and the creationof a relatively high vacuum at the intake side of the second stage.

23. The process of compressing and condensing a vapor, pressing and pumping said vapor with a rotating body ofthe liquid of the vapor as the pumping medium, through a pluralit of successive stages, and cooling the gas an liqpumped to maintain a low vapor pressure of the pumping liquid, whereby breaking of the vacuum in the second stagee by the vvaporization of the liquid will avoided.

` 'WILLIS H. CARRIER.

which comprises com- 

